I guess that depends on how you want to use Skype. If you are going to use it to make a lot of calls to people who don't have Skype, then I guess you'd want to buy Skype Pro. I don't know what Skype In is. If you're going to be calling someone all the time, tell them to get Skype too, then you don't have to buy anything because Skype to Skype calls are free.